Fig. 5. Urinary excretion rates of woodchucks and rabbits before and during prolonged fasting. (A) Absolute rates of N excretion (N=4 for spring and summer woochucks, N=9 for rabbits). (B-E) The relative contributions of urea (B), ammonia (C), creatinine (D) and uric acid (E) to total N excretion. For relative contributions (% of total N excretion), the values for spring and summer woodchucks were pooled (N=8 for woodchucks and 9 for rabbits). Values are means ± S.E.M. ^*Significant differences from fed values measured on day 0 within each group.